Low Coordinate Germanium(II) and Tin(II) Hydride Complexes: Efficient Catalysts for the Hydroboration of Carbonyl Compounds

This study details the first use of well-defined low-valent p-block metal hydrides as catalysts in organic synthesis. That is, the bulky, two-coordinate germanium(11) and tin(11) hydride complexes, L-dagger(H)M: (M = Ge or Sn, L-dagger = -N(Ar-dagger)(SiPr3i), Ar-dagger = C6H2{C(H)Ph-2}(2)Pr-i-2,6,4), are shown to act as efficient catalysts for the hydroboration (with HBpin, pin = pinacolato) of a variety of unactivated, and sometimes very bulky, carbonyl compounds. Catalyst loadings as low as 0.05 mol % are required to achieve quantitative conversions, with turnover frequencies in excess of 13 300 h(-1) in some cases. This activity rivals that of currently available catalysts used for such reactions.